The present invention relates to an image forming apparatus for use as, for example, an electrophotographic copier, for ejecting a sheet on which an image is transferred to a sheet receiving unit of an apparatus body.
An image forming apparatus such as an electrophotographic copier comprises a document table glass on which a document is to be placed, on an upper part of the apparatus body. An image scanner for optically scanning an image of the document is provided under the document table glass. The image information scanned by the image scanner is formed as an electrostatic latent image on a photosensitive drum. A developer is supplied to the electrostatic latent image by a developing unit and, therefore, the electrostatic latent image becomes a developer image. The developer image is transferred to a sheet, which is regarded as an image-transferred material. The sheet on which the developer image is transferred is conveyed by a conveyance mechanism. The transferred image is fixed on the sheet by a fixing unit during the conveyance and then the sheet is ejected.
Incidentally, the sheet is ejected to the outside of the apparatus body to simplify the structure of the apparatus body or to convey the sheet linearly.
On the other hand, recently, the apparatus allowing the sheet to be ejected to the sheet receiving unit provided inside the apparatus body while making the printed surface of the sheet face downward has been developed in order to maintain the secrecy of a document image printed on the sheet, to make the distance of conveyance of the sheet shorter, and to save the space. The sheet ejected to the sheet receiving unit is heated at the fixing unit before the ejection. The sheet therefore emits the heat inside the sheet receiving unit.
However, the image scanner is positioned at the uppermost part of the apparatus body when the function thereof is considered, and the sheet receiving unit is arranged immediately under the image scanner. Thus, the temperature of the image scanner is raised by the heat emitted from the sheets collected in the sheet receiving unit. As the image scanner comprises the optical components and the electronic components, the rise of the temperature causes a problem that a bad influence may be given to the performances of the optical components and the electronic components and thereby the image may be deteriorated.
To prevent the rise of the temperature of the image scanner, suction of outside air by use of a fan or the like to cool the image scanner is conceived.
However, the image scanner contains the optical components and is easily affected by dust and the like. For this reason, it is desirable not to provide an opening portion such as an air inlet on the image scanner, and it is not preferable to cool the image scanner by sucking the outside air into the image scanner.